function changeTabs(moveTo) {
  var currentTab = document.tabForm.tabSet.value
  var totalTabs = document.tabForm.totalTabs.value

 
  if (moveTo == 'next') {
    var thisTab = addNumbers(currentTab,1)
    toggleOn('prev-tabs');
    if (thisTab == totalTabs) {
     toggleOff('next-tabs');
    }
  } else {
    var thisTab = subtractNumbers(currentTab,1)
    if (thisTab == 1) {
     toggleOff('prev-tabs');
    }
    if (thisTab != totalTabs) {
     toggleOn('next-tabs');
    }
  }

    document.tabForm.tabSet.value = thisTab;

    toggleOff('set'+currentTab);
    toggleOn('set'+thisTab);

} 



function addNumbers(a,b)
{
	var c = parseInt(a)+parseInt(b);
	return c;
}
function subtractNumbers(a,b)
{
	var c = parseInt(a)-parseInt(b);
	return c;
}